Bit with protected insert



BIT WITH PROTECTED INSERT Original Filed March 8, 1946 INVENTOR.

Patented Sept. 27, 1949 BIT WITH PROTECTED INSERT Harry M. Morrow, Canton, Ohio, assignor to The Bowdil Company Original application March 8, 1946, Serial No. 652,972. Divided and this application June 10, 1949, Serial No. 98,267

6 Claims.

My invention relates in general to cutting bits and more particularly to bits for cutting coal or other substances.

This application is a division of my copending application Serial No. 652,972, filed March 8, 1946, and entitled Bit, and is directed primarily to the subject matter of Figures 1 through 16. However, in order to maintain continuity between application Serial No. 652,972 and the present application, the remainder of this specification and the drawings are exact duplicates of application Serial No. 652,972.

In the mining of coal or other substances, a cleft is cut in the lower level of the vein by means of a cutter bar around which revolves a power driven endless chain carrying a plurality of cutting bits arranged in staggered relationship relative to one another. These cutting bits constitute the subject matter of this invention. The shelf formed by the cleft is subsequently broken off by means of explosives or other suitable methods. When cutting the cleft, in the interest of economy and the saving of power, it is highly desirable that the cutting bits be not only strong and durable, but also efilcient in operation and free from drag. Further, it is desirable that these bits present a cutting tip which is long lived and resistant to rapid wear in order that the power driven endless chain carrying the bits may be operated continually until a specific cut is completed. That is, it is desirable that the bits be durable to withstand prolonged abrasive action in order to prevent costly delay in removing the endless chain machine from the cleft before the cleft is finished in order to replace worn bits.

Therefore, an object of my invention is to provide a cutting bit having an extremely hard cutting tip.

Another object of my invention is to provide a cutting bit having a tough and durable body and having an extremely hard cutting tip imbedded therein.

Another object of my invention is the provision of a hard metal insert for the body of a cutting bit which will provide an extremely durable end cutting edge for the bit, and is protected against dislodging impacts by the tough body metal of the cutting bit.

Another object of my invention is the provision of an extremely hard insert for a cutting bit to provide a durable end cutting surface for the bit with the insert automatically exposable by the wearing away of the bit body.

Another object of my invention is to provide a cutting bit having steel side cutting surfaces inclined in the direction of travelfor slicing cutting action, and having a hard metal cutting tip insert substantially perpendicular to the surface being cut to provide impact cutting.

Yet another object of my invention, is to provide a cutting bit with a hard metal insert at the cutting tip thereof, with the hard metal insert positioned to contact a surface and cut the surface when the bit is moving in a cutting direction, and said bit having a protecting surface to protect the hard metal insert from dislodging from impacts when the cutting bit is moving in a direction other than the active cutting direction.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational view of a rhomboidal shaped coal cutting bit blank to be developed into a bit employing the principles of my invention;

Figure 2 is a side elevational view of the rhomboidal shaped coal cutting bit of Figure 1 with a phantom outline at one cutting tip of a groove provided therein, and showing a portion broken away at the opposite cutting end to reveal the slot.

Figure 3 is a fragmentary portion of a bit with a portion thereof broken away and showing greatly exaggerated a layer of bonding flux on the surface of the slot walls;

Figure 4 is a View similar to the Figure 3 with a hard metal insert and a piece of bonding material positioned in the slot with the bonding flux between the slot surface walls and the insert;

Figure 5 is a cross-sectional view along the line 55 of Figure 3;

Figure 6 is a cross-sectional view along the line 66 of Figure 4;

Figure '7 is a side and front view of the commercial finished product;

Figure 8 is a front view of the bit after a period of service, or after being dressed by abrasive action;

Figure 9 is a side elevational view of a rhomboidal shaped coal cutting bit blank to be developed into a bit employing the principles of my invention;

Figure 10 is a side elevational view of the rhomboidal shaped coal cutting bit of Figure 9 with a phantom outline at one cutting tip of a recess provided therein, and showing a portion broken away at the opposite cutting end to reveal the recess;

Figure 11 is a fragmentary portion of a bit with a portion thereof broken away and showing greatly exaggerated a layer of bonding flux on the surface of the recess walls;

Figure 12 is a View similar to the Figure 11 with a hard metal insert and a piece of bonding material positioned in the recess with the bonding flux between therecess surface walls and the insert;

Figure 13 is a cross-sectional View along the line l3-l3 of Figure 11;

Figure 14 is a cross-sectional view along the line l4l4 of Figure 12;

Figure 15 is a side and front view. of the commercial finished product;

Figure 16 is a front view of the bit after a period of service, or after being'dressed'by abra-g sive action; and

Figure 17 is a diagrammatic illustration of the relative position of a cutting bit carried by an endless chain link, showing the bit in its active cutting positioncand in fits-backing. drag position.

With reference to the drawings,-I illustrate my invention in its'preferred embodiment as incorporated in a rhomboidal shape'cl -coalcutting bit.

This invention, however, is not limited to bits of rhomboidalshape, but may be readily employed in. other types of coalcutting bits, as well as in cutting tools for 1 other "purposes! in which the mode of cutting is similar. In the'mining of coal,

these bits are :removably mounted in'the lugs of an endless power driven chain which revolves around a cutter-bar. -I-Shisdevice is then moved against the face of -a-coal veinand-atcleft is cut under-the vein of-coaln. .Each bit is adapted to contact the 'coal rsurfacecand carve a furrow therein.- In carvingits furrow,-the tip of the bit is forced into the. coalnandservestochip out minute piecesof-thecoal-tostartthe' furrow. The side edges of the bit serve to chip away the sides of the furrow and widen the furrow in order that the next bit 1 be able to descend totthe depth of thefurrowiandcarve anew and deeper furrow. :Thus, the tip ofathe bit receives considerably greaterzwear than thesides of the bit, and is subject to :much-more severe wearing conditions than the side. In the particular form oilrhomboidal bit as illustrated, when one of the cutting points of the bit wears-away, the bits are reversible inthe holden-agiving a. double cutting life to the bit. It is extremely. desirable to provide a cutting bit which is ableto w-ithstand the extreme wearing.- conditions. imposed and maintain an activelcutting tip throughout the period of cutting..--the-.cleft inorderithat the cutting operation-willwnot berequiredto be halted in order to reverse or replace the bits.

Inthe Figures .1 through 8,! have illustrated one embodiment of my invention.v The :Figure l is a side elevational view of la. rhomboidal shaped bit It preferably constructed of tough alloy steel and similar tovrthe -rhomlooida-l bit shown in Patent vNo.. 1,f5'77,9,5[l, issued to N. K..-Bowman on July 24, 192 8, and Patent No. 2,217,847, issued to Morrow on Gctober 8,-1940, bothpatents of which are assigned to' the assignee of the present application. -This .bit 1-0 is used as the bit blank in preparing a bit employing the principles ofthe present --invention. sFigure 2 of: the drawings illustrates in: phantom and in a broken away-portion thed-epth-andoutline form of a groove which maybemilled. orotherwise cut into thetip of the bit; .-'-The cutting of the groove produces two side portions 14 and i5. 'After this groove ll is out, a-coating oflfiux-material i2 is coated over -the. surface ofwthe groove H, This bya silver solder or other suitable bonding mate- 7. rial. -.In the illustration, I show a piece of silver solder 16 held in the groove in a position rela- Etivelyr near to'theinsert 13 by pinching in the sideportions l iand l5 in a manner similar to that of the insert H3. The bit ill with the insert l3 and-the bonding material It held frictionally within the groove H is then placed in a heat treating furnace and elevated in temperature. During the time'which thedevice is held at the elevated temperature, the bonding-material H5 is caused'to become fluid and will work its way between thelnsert l3 and the walls of the side portions l4 and 15 by capillaryaction. The flux l2 assists both in the capillary action, and in the forming of a good. bond between the material oi the bit it and the material of the insert [3 with the bonding material 16. After a predetermined length of time, the bit is removedfrom the elevated temperature Zone and rapidly cooled by quenching in oil or molten salt according to the well-known method of heat treating ferrous material, in order to-harden the-tough alloy steel comprising the bit it and the side portions Idand i5; :Thuathe'bit: iii appearsasin the Figure '7 of .the' drawings. 5:111 this figure, it will'be seen, that the bit comprises a bit body ill of hardened alloy steel, andhaving a side portion Id and a side portion: 15 with a groove H therebetween. The sideportions is and l5 and the groove Ii merge with the remainder of the active cutting face 17: of theabit as: illustrated. The insert I3 is permanently bonded in the groove H by the bonding material 16, which-has-replaced the flux material 12.

.In the position as illustrated-,- the insert l3 extends to the tip region of thebit It, and presents an active cutting edge l8 to-contact the material tobe cut by-the tip of thebit. Also apparent from the Figure 7, are two side cutting edges ll: and 20 on the side portions I l and I5, respectively. These side cutting edges serve to cut and widen a furrow dug by the cutting edge if; pre sented by the insert I3.

'Fromapast' experience, ithas been found that the side cutting edges 49 and .26 will operatemore satisfactorily when inclined at an angle to the surface being cut. :That is, the side cutting edges 13 and 28 should preferably have an askew action. :However, when using hard and brittle materials as an insert, it has been found that an impact surface is most operative. Therefore, the insert 13 is positioned at an angle to the cutting face H, as illustrated in the Figure 7. .This relationship of the side cutting edges id and zliand the endicutting edge i8 is further illustrated in the Figure 17..

In the Figure 7, the side portions 14 and it are illustrated with tworel-atively sharp points 25 and 22-on the sideportions l4 and i5 respectively. In this particularmodificatiion of the invention, the sharp points 2! and 22 are incidental to manufacture; These sharp points will soon: wear away or ibreakuoiiaafter theibitf 1B is mounted in the cutter chain and placed in operation. Thereafter the cutting edge I8 will be exposed for active cutting service. However, these sharp Points 2! and 22, as well as a portion of the side portions l4 and [5, may be removed .by grinding before the bit in is placed in operation if desired, as shown in Figure 8. As before indicated, these excess portions are automatically removed after a period of actual cutting operations, and therefore, for all intents and purposes the bit l may be placed in operation as illustrated in the Figure '7. After the bit ill has been placed in operation for a period of time, or after the excess portions have been removed by grinding, the bit will appear as illustrated in the face view in Figure 8. Therefore, although the finished bit as presented to the operators will preferably be furnished as shown in the Figure '7,

the actual working bit will appear substantially as shown in the Figure 8.

The insert l3, as before explained, is provided for thepurpose of furnishing an end cutting surface for the bit which is extremely durable to prolong the active cutting life of the bit. Therefore, an extremely hard material is preferable for s the insert l3. The type of material available for this purpose includes sintered metal products which have been developed and which are suitable for this purpose. Carboloy i an example of one such material. These materials are so extremely hard, that practical methods of forming or shaping a product after once being sintered have not been found. Abrasive action, such as by a grinding wheel, is the only means available today to work or form a sintered product after sintering. The sintered material, however, is extremely brittle and possesses a relatively low tensile strength. Therefore, it must be protected against bending stresses and pulling or tensile stresses. the product, then, is its extreme hardness and resistance to wear, but it must be protected by a backing surface of a more ductile although softer material, such as ferrous products from which the :bit I9 is made.

My improved structure provides the protection required to make the use of a hard metal insert !3 practical. In my structure, the side portions l4 and !5 protect the sides of the insert 13 in such a manner that side impacts against a portion of the insert which is not backed up by a backing member will be prevented. But when the cutting bit is advancing in the direction of its active cutting face H, the insert [3 will present a cutting edge l8 which will be entirely backed up by the tougher but softer metal of the bit 10. The portion of the bit Ill lying directly back of the insert l3 and serving as the backing therefor may be designated as the backing portion 23 of the bit II].

In operation, as previously explained, the excess material surrounding the tip of the insert I3 will be removed by the abrasive action of the cutting operation. Thereafter, the edge l8 of the insert 13 will be exposed to contact the surface to be cut. The edge 18 will cut a considerably larger quantity of material than the hardened alloy steel from which the bit I!) may be made. As the wearing continues during the cutting operation, the side portions l4 and [5 will be steadily worn back to continually expose more of the insert 13. That is, as the bit moves in its cutting operation, the insert cutting edge l8 will be worn back slowly, but as it is worn back the side portions [4 and I5 will be worn back also The most desirable characteristic of to continually expose the cutting edge I8. Also during the cutting operation, the cutting edges I9 and 20 of the portions l4 and [5 will remove the side surfaces of the furrow being cut and enlarge the furrow for the next bit to enter. By this arrangement of parts in my improved cutting bit, therefore, I have provided a cutting bit having a cutting edge which is a composite of at least three cutting edges. That is, the cutting edge for the bit as it is produced and illustrated in the Figure '7, will comprise the side cutting edges [9 and 2E and the end cutting edge l8. These cutting edges constitute a composite cutting edge for the bit and by the several edges operating in conjunction with one another they will contact the entire surface of the furrow being out. Of course, after a period of use or after the bit If! is ground as illustrated in the Figure 8, the cutting edge It of the insert I3 and the side cutting edges l9 and 29 will be combined to form a continuous cutting edge which will make the entire out together as one unit.

The Figures 9 through 16 illustrate a second alternative method of producing a bit in accordance with the principles of my invention. In this modification, a recess opening 24 is provided in the bit [0 from a flattened end surface 2 5, and the bottom of the recess extends to the face of the cutting bit. As illustrated, this recess opening 24 is provided at an angle to the surface I! substantially the same as the angle which the insert it will assume in the modification illustrated in the Figures 1 through 8. An insert 26 is provided to be placed in the opening 24 and is bonded thereto in a manner similar to the method discussed in connection with the bonding of the insert 13 in the groove H. Gases formed during the bonding operation may escape from the recess through the bottom thereof. The cutting bit produced by this mode of construction will operate in substantially the same manner as the manner described in connection with the insert l3, with the possible exception that a protecting surface will be provided by the walls of the opening 2d completely around the insert 26 until the end thereof is exposed by wear of the hardened alloy steel bit body as previously explained.

During the operation of cutting a cleft for the coal with the coal cutting machine carrying the bits thereabout, the bit often encounters an obstruction which will require a smaller cut for each revolution of the chains, or an excess of loose materials will bind the machine, or other conditions will happen which will require the cutting chain to be reversed for a period of time in order to free the chain. Thus, the cutting bit It will not always be operating in a forward position, but will often be backing up away from its cutting direction. During this backing up period, the bit will drag across the surface of the coal, and will also encounter material which will deliver impact blows to the bit. With cutting machines employing endless chains as described, there is a considerable amount of opportunity for the individual links of the chain which carry the bits to be displaced from their normal free running position when outside forces are experienced. That is, during the cutting operation, a large leverage force is applied to the link and. bit due to the driving force on the link and the draggi force on the tip of the cutter bit. It will readily be seen, therefore, that the links will tend to lean over backwards in a direction opposite to the direction of travel. Therefore, the bit holder and the bit are provided to compensate for this destruction of the bits usefulness; .struction has taken cognizance of this danger imposed upon the hard metal-insert when the bit area-221 aim-p nt ormovement and prese t the b t to he cutti g sur a e a the proper cu i an e- Thi sit n is l u tra ed by the full heavy lines 11- lust ated' v the referenc 'c arac .8 i the Fig re 17.- .Likewi e, wh n the c n machine is reversed and th drag is on the opposite side of the cutting tip, the links will tend to flop over to t e o h r ex r me, and i ill trat d dia ramm t a y by thedot-da h l ne i di ated y the ref rence haracter 29 f Fi re 17.

, .As previously explained, the hard material from which the inserts are made iszvery brittle and has little resistance to bending stresses, tensile stresses and chipping action. Therefore, a bit construction which does not fully protect the insertfrom chippingactions on the side thereof,

or impacts from the reverse direction on the cutting edge, will allow chipping and consequent My bit conis traveling in a reverse direction. It will be seen, that in each of the modifications of the cutting bit shown, that if the bit It be. tilted into the position as illustrated in the diagrammatic dot-dash position :29 of Figure 17, a protecting surface is provided by thebacking portion 23 to take all direct blows and protect the insert. For example, the bit illustrated in the Figure 1'7 may be considered to be either the modification illustrated in the Figure *7 or the Figure 8 after the bit has been worn to remove the excess bit material. At all times in the life of the bit, and particularly after. having been worn for some period of time, the bit backing portion 23 will provide a definite backing for the insert even at the extreme end thereof. As wear continues, the portion backing the cutting tip of the insert will be even greater. In the Figure 17, the dotted line 33 pictures diagrammatically the bottom of a furrow cut in the face 31 of a vein of coal 32. It will be seen, from this illustration, that the end of thebit has been worn flat on the tip thereof by the abrasive action of the coal and has provided a corner 33 on the bit backing portion 23. This corner 33 acts as a bumper to ward ofi impact blows and protect the insert when the bit is moving in a reverse direction. This safety feature, coupled with the protecting side walls surrounding the bits, serves to protect the insert and protects it from impact blows that would destroy the insert and the usefulness of the bit in a period of time without this protection.

Although my invention has been. described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combine..- tion and arrangement of parts may be resorted to without departing from the spirit andthe scope of the invention as hereinafter claimed.

What is claimed is:

l. A cutting bit, comprising a bit body provided with a cutting endand having an active cutting We and a face backing portion, a recess extending from said backing portion to said active cutting elongated hard metal insert positioned in d recess, the longitudinal axis of "the hard metal insert sloping rearwardly away from the cutting face and defining an acute included angle between the said axis and said face, said insert being exposable by the wearing away of the active cutting face. I

2. A- cutting bit, comprisin a bit body provided with a cutting end and having an active cutting faceand a face backing portion, a longitudinal bore extending from said backing portion to said active cutting face, an elongated hard metal insert positioned in said bore, the longitudinal axis of the hard metal insert sloping rearwardly away from the cutting face and defining an acute included-angle between the said axis and said face, said insert being exposable by the wearing away of the active cutting face.

3. A cutting bit,,comprising a bit body provided with a cutting end and having an active cutting face. and-a face backing portion, a recess extend- ;ing from said backing portion to said active cutting face, an elongated hard metal insert positicned in said recess, the longitudinal axis of the hardmetal insert sloping rearwardly away from the cutting face and defining an acute included angle between the saidaxis and said face, said insert being exposable by the wearing away of the active cutting face, the exposed portion of said insert and said face side cutting surf-ace forming a continuous cutting edge for the bit.

a. Acutting bit comprising a bit body having a firs-tportion with a, face area and a cutting edge and a second portion with a face area and. a .cut

ting edge, said face areas definingthe cutting face of the bit, said first and second portions forming a groove therebetween, an elongated metal insert harder than said bit first and second portions mounted in said groove, the longitudinal axis of the hard metal insert sloping rearwardly away from the cutting face and defining an acute included angle between the said axis and said face, said insert having an end cutting ,surface, said first and second portion cutting edges and said insert end cutting surface forming a composite cutting edge for said bit, said insert being exposable by the wearing away of the first and second portions.

5. A cutting bit comprising a bit body having a first portion with a face area and a cuttin edge and a, second portion with a face area and a cutting edge, said face areas defining the cutting face of the bit, said first and second portions forming a groove therebetween, an elongated metal insert harder than said bit first and second portions mounted in said groove, the

longitudinal of the hard metal insert sloping rearwardly away from the cutting face and defining an acute included angle between the said axisand said face, said insert having an .end cutting surface, said first and second portion cutting edges and said insert end cutting surf-ace forming a continuous cutting edge for the bit, said insert being exposable by the wearing away of the first and second portion cutting edges.

6. Adouble ended bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces offset relative to one another, cutting tips at the diametrically opposed sharper angles of the rhomboid, a recess extending downwardly from each to an adjacent cutting face, an elongated hard metal insert receivable in said recess, the longitudinal axis of the bard metal insert sloping rearw-ardly away from the cutting face and defining an acute included angle between the said axis and said face, and bonding means to bond said insert to the walls of said recess.

HARRY M. MORROW.

No references cited. 

